title: Correlation between sustained c-Jun N-terminal protein kinase activation and apoptosis induced by tumor necrosis factor-alpha in rat mesangial cells.
abstract: Rat mesangial cells are normally resistant to tumor necrosis factor-alpha (TNF-alpha)-induced apoptosis. In this report we show that the cells can be made susceptible to the apoptotic effect of TNF-alpha when pretreated with actinomycin D, cycloheximide, or vanadate. c-Jun N-terminal protein kinase (JNK) has been thought to mediate apoptotic processes elicited by some stimuli, but its involvement in TNF-alpha-induced apoptosis has been controversial. JNK activation was investigated under conditions where the mesangial cells were either resistant or susceptible to TNF-alpha-induced apoptosis. TNF-alpha alone stimulated a single transient JNK activity peak. However, when the cells were pretreated with actinomycin D or cycloheximide, TNF-alpha stimulated a second sustained JNK activity peak. When the cells were pretreated with the phosphatase inhibitor vanadate, TNF-alpha-induced JNK activation was greatly prolonged. In all three cases, a sustained JNK activation was associated with the initiation of apoptosis. Our data suggest that a sustained activation of JNK induced by these reagents may be associated with blocking the expression of a phosphatase that inactivates JNK. Further studies reveal that the expression of mitogen-activated protein kinase phosphatase-1 (MKP-1) was induced by TNF-alpha, indicating that MKP-1 may be involved in protecting the cells from apoptosis by preventing a prolonged activation of JNK under normal conditions. Additional studies showed that extracellular signal-regulated protein kinase activation stimulated by TNF-alpha was unlikely to contribute to the resistance of mesangial cells to TNF-alpha cytotoxicity.
authors.affiliation: Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Y L
authors.initials: YL
authors.lastname: Guo
authors.forename: K
authors.initials: K
authors.lastname: Baysal
authors.forename: B
authors.initials: B
authors.lastname: Kang
authors.forename: L J
authors.initials: LJ
authors.lastname: Yang
authors.forename: J R
authors.initials: JR
authors.lastname: Williamson
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D018797:Cell Cycle Proteins; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D054638:Dual Specificity Phosphatase 1; D004789:Enzyme Activation / Q000502:physiology; D005920:Glomerular Mesangium / Q000166:cytology / Q000201:enzymology*; D017874:Immediate-Early Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases; D016328:NF-kappa B / Q000378:metabolism; D019319:Okadaic Acid / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D014638:Vanadates / Q000494:pharmacology
chemical_list: D018797:Cell Cycle Proteins; D017874:Immediate-Early Proteins; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D003609:Dactinomycin; D019319:Okadaic Acid; D014638:Vanadates; D003513:Cycloheximide; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D054638:Dual Specificity Phosphatase 1; C517021:Dusp1 protein, rat; D017027:Protein Tyrosine Phosphatases